1. Field of the Invention
The present invention generally relates to suspension systems for two-wheeled vehicles, such as mountain bikes and motorcycles, and, more particularly, is concerned with an electronically controlled anti-dive suspension apparatus for actively adjusting the front suspension of the two-wheeled vehicle to counteract the initiation of a dive condition due to xe2x80x9chardxe2x80x9d braking by the cyclist.
2. Description of the Prior Art
In recent years suspension systems on bicycles, particularly on mountain bikes, have become more common. Some examples of bicycle suspension systems are the ones disclosed in U.S. Pat. No. 4,679,811 to Shuler, U.S. Pat. No. 4,881,750 to Hartmann, U.S. Pat. No. 5,044,648 to Knapp, U.S. Pat. Nos. 5,308,099 and 5,509,674 to Browning, U.S. Pat. Nos. 5,445,401 and 5,509,677 to Bradbury, and U.S. Pat. Nos. 5,456,480 and 5,580,075 to Turner et al.
A common drawback of most suspension systems is that they are passive mechanical systems which do not sense change in riding conditions nor automatically adjust in response thereto. This results in suspension systems that may be too stiff for extremely rocky, steep descents and too soft for riding on surfaced roads and bike paths. Some suspension systems allow the rider to adjust the pretension on the suspension components. However, this process normally requires stopping the bicycle to manually make the necessary adjustments. The rider must estimate the stiffness or softness that might be required for the anticipated riding conditions. Also, the adjustments in some of these systems require the use of tools.
The above-cited Turner et al. U.S. Pat. No. 5,456,480 contains a caution to designers that electronic control of bicycle suspensions is impractical. This statement seems intended to discourage any attempts to improve bicycle suspensions through the development of an electronically-based solution to controlling the suspensions in order to adjust to different riding conditions. Nevertheless, it is the perception of the inventor herein that a different approach, possibly one that is electronically-based, is needed in the design of suspension systems for two-wheeled vehicles, such as on mountain bikes and motorcycles, to improve their handling and performance.
This is especially the case during xe2x80x9chardxe2x80x9d braking of the mountain bike or motorcycle by the cyclist when it is common for the front suspension to xe2x80x9cdivexe2x80x9d causing the vehicle to rock forward. Then, once braking has stopped, the suspension causes the bike to xe2x80x9crockxe2x80x9d back. Such rocking motion can be particularly hazardous for a cyclist on a mountain bike during a steep descent which in combination with hard braking can result in the cyclist flying over the handlebars and for a cyclist on a motorcycle while hard braking prior to entering a sharp corner followed by an acceleration when exiting the corner.
The present invention provides an electronically controlled anti-dive suspension apparatus for a two-wheeled vehicle designed to satisfy the aforementioned need. The anti-dive suspension apparatus of the present invention employs an electronics module, sensor means, actuator means and power source in conjunction with a front suspension on a two-wheeled vehicle for actively adjusting the front suspension of the two-wheeled vehicle to counteract the initiation of a dive condition due to braking by the cyclist. The sensor means actively senses the deceleration of the vehicle due to the application of the brakes and produces signals representative thereof as inputs to the electronics module which processes the inputs and produces an output causing activation of the actuator means to adjust the front suspension system to xe2x80x9cstiffenxe2x80x9d it so as to prevent its contraction and the resulting dive of the front end of the vehicle downward toward the front wheel and thus the ground.
Accordingly, the present invention is directed to a electronically controlled anti-dive suspension apparatus for use on a two-wheeled vehicle. The apparatus comprises: (a) a front suspension system mounted to and between first and second parts of a two-wheeled vehicle movable relative to and toward one another in response to a braking action being applied to the vehicle, the front suspension system including first means connected between the first and second relative movable parts of the vehicle and being contractible in response to the first and second vehicle parts moving toward one another due to the braking action and second means connected to the first means for controlling the amount of contraction of the first means; (b) means mounted to either one of the first and second relative movable parts of the vehicle for sensing deceleration of the vehicle due to the braking action and producing an input representative thereof; (c) an electronics module mounted to the vehicle and connected to the sensing means for receiving and processing the input from the sensing means to produce an output corresponding to a desired predetermined response to the deceleration of the vehicle sensed by the sensing means; (d) at least one actuator mounted to the vehicle and coupled to the suspension system for receiving the output from the electronics module and in response thereto causing the second means of the suspension system to reduce the amount of contraction of the first means and thereby prevent the resulting dive of the front end of the cycle downward toward the ground; and (e) means for electrically powering the sensing means, the electronics module and the at least one actuator.
More particularly, the first means of the suspension system includes a cylinder having telescoping members defining an interior cavity and respectively connected to the first and second parts of the vehicle movable relative to one another and movable toward and away from one another between predetermined limits, and an extendable and contractible spring disposed within the interior cavity being biased to force the telescoping members away from one another. The second means of the suspension system includes a fluid contained in the interior cavity and a partition fixed across said interior cavity inside one of the telescoping members to divide the interior cavity into separate chambers in the telescoping members. The partition defines at least one orifice having a predetermined size for controlling a rate of flow of the fluid between the chambers of the telescoping members so as to control the contraction of the spring and thereby control the movement of the telescoping members toward one another. The actuator is coupled to the cylinder of the first means of the suspension system and movable relative thereto to change the size of the orifice of the partition of the second means of the suspension system. The sensing means preferably is an accelerometer. The electrical powering means preferably is at least one battery.
These and other features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention.